1. Field of the Invention
The present invention relates to a visitor conversation system whereby a visit of a person is detected and a conversation may be conducted. Also, the arrival of a vehicle may be detected and a conversation conducted if the vehicle is carrying an ultrsonic conversation device.
2. Description of the Prior Art
Conventional systems are available in which a visit of a person is detected by a combination of a light emitter and a light receiver as the person interrupts the path of the light between the light emitter and the light receiver. Conventional systems are also available having the sole function of holding a conversation on wire with a visitor by such means as an intercom located on the front door of a house, or in which a person with a transceiver in a vehicle can talk with another person outside the vehicle.
None of these systems have dual functions of detection of and conversation with a visitor, and such a dual-purpose system, if realized conventionally, would require separate circuits for detection and conversation, with the result that the circuit configuration is complicated for an increased production cost.